Oh I see. So maturity is what defines "adult" to you. Sadly, this is a poor measure, for the simple reason "maturity" is open to interpretation. Age is not, which is why I prefer this measure.

Being petulant and obnoxious is not behaviour exclusive to children. We're talking about a 70 y/o billionaire here. Saying he's not an adult is about as effective insult as saying he's not American.